The invention relates to a device for an internal combustion engine having a main coolant pump supplying coolant to the internal combustion engine including a large cooling circuit with an air/coolant heat exchanger and a small cooling circuit by-passing the air/fluid heat exchanger and a coolant/oil heat exchanger which bypasses the air/coolant heat exchanger and a coolant/oil heat exchanger for heating or cooling the oil of a transmission of the internal combustion engine.
DE 196 37 817 C1 discloses a device and a method for cooling and preheating in particular transmission oil in internal combustion engines. The device has a cooling circuit including a coolant pump, and an air/fluid cooler which can be connected into the cooling circuit by means of an engine thermostat when a specific temperature is reached. Furthermore, the device has a heat exchanger through which a coolant of the cooling circuit of the internal combustion engine and transmission oil flow. This heat exchanger can be used to heat and to cool the transmission oil. In order to heat the transmission oil, a control unit branches off a flow of coolant from a main cooling circuit of the internal combustion engine, said flow of coolant transferring thermal energy to the transmission oil in the heat exchanger. In the cooling phase, the control unit feeds a flow of coolant for cooling the transmission oil from a low temperature cooler into the heat exchanger. The control unit has two thermostats, one thermostat ensuring that the hot flow of coolant for heating the transmission oil is regulated, i.e. the thermostat is opened at a cold coolant temperature and closes at a predetermined, higher temperature. In the case of cooling, the other thermostat regulates the flow of coolant coming from the low temperature part of the water cooler in such a way that a predefined constant transmission oil temperature can be realized. At a low coolant temperature, this thermostat is closed and opens at a predeterminable higher temperature.
It is the object of the present invention to provide a device for cooling and heating transmission oil in internal combustion engines which has a simplified design compared to the prior art and which improves the heating of the internal combustion engine after a cold start.